By 2030, about 70% of deaths attributed to tobacco use will occur in low- and middle-income countries, accounting for more than 10 million deaths globally. India, the second largest country in the world, provides an important case example for tobacco control. The Report on Tobacco Control in India conservatively estimated that tobacco-attributable deaths in India currently range from 800,000 to 900,000 per year, costing US$7.2 billion in 2002-2003. There is urgent need for evidence-based interventions that can stem the epidemic and reduce the burden of tobacco use. Reducing tobacco use in India likely will have profound impact on mortality and morbidity not just in India but also globally. As a signatory to the Framework Convention for Tobacco Control (FCTC), success in the Indian case could provide important lessons for tobacco control across the globe. Worksites provide a ready channel for reaching large numbers of tobacco users. In Indian worksites, medical officers and occupational health and safety offices provide an infrastructure from which to build tobacco use cessation policies and programs. The proposed study will adapt an evidence-based tobacco control intervention for application within Indian manufacturing worksites. This intervention model integrates worksite health promotion interventions with occupational health and safety, and has been shown to be efficacious in promoting smoking cessation, particularly for blue-collar workers. We will test this comprehensive tobacco control intervention in manufacturing worksites in Mumbai using a randomized controlled design, with the worksite as the unit of intervention and randomization. We will assess efficacy in terms of two outcomes: increased cessation of tobacco use among workers in participating worksites (primary outcome), and increased adoption and enforcement of worksite tobacco control policies (secondary outcome). We will additionally examine the role of mediating mechanisms and modifying conditions specified in our conceptual model. We will use process evaluation to assess the adaptation process within worksites, the extent of implementation of the intervention in worksites adopting the program, and worker participation in the program in worksites assigned to the intervention condition. If demonstrated to be effective, this study will result in a tested worksite tobacco control intervention ready for dissemination in India, and able to inform worksite tobacco control in other developing countries. Our close collaborative partnerships in India and the US, our diverse research team of members from India and the US, and extensive partnerships with industry and occupational health groups in India will facilitate the adoption of a successful program of policy intervention. PUBLIC HEALTH RELEVANCE: India provides an important case example of tobacco control efforts within a developing country, as the second largest country in the world and a solid foundation for tobacco control already in place. The purpose of this study is to adapt an evidence-based worksite tobacco control intervention for application to Indian manufacturing worksites, and test the efficacy of this intervention using a randomized controlled design, with the worksite as the unit of intervention and randomization. This study extends a well-established partnership between researchers in the US and India.